[PATCH 6.18 15/49] smb: client: let recv_done() queue a refill when the peer is low on credits

Greg Kroah-Hartman
2026-02-13T13:52:35Z

From: Stefan Metzmacher <metze@samba.org>

commit defb3c05fee94b296eebe05aaea16d2664b00252 upstream.

In captures I saw that Windows was granting 191 credits in a batch
when its peer posted a lot of messages. We are asking for a
credit target of 255 and 191 is 252*3/4.

So we also use that logic in order to fill the
recv buffers available to the peer.

Fixes: 02548c477a90 ("smb: client: queue post_recv_credits_work also if the peer raises the credit target")
Cc: <stable@vger.kernel.org> # 6.18.x
Cc: Steve French <smfrench@gmail.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Long Li <longli@microsoft.com>
Cc: Namjae Jeon <linkinjeon@kernel.org>
Cc: linux-cifs@vger.kernel.org
Cc: samba-technical@lists.samba.org
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/smb/client/smbdirect.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

--- a/fs/smb/client/smbdirect.c
+++ b/fs/smb/client/smbdirect.c
@@ -663,6 +663,7 @@ static void recv_done(struct ib_cq *cq,
container_of(wc->wr_cqe, struct smbdirect_recv_io, cqe);
struct smbdirect_socket *sc = response->socket;
struct smbdirect_socket_parameters *sp = &sc->parameters;
+ int current_recv_credits;
u16 old_recv_credit_target;
u32 data_offset = 0;
u32 data_length = 0;
@@ -747,7 +748,8 @@ static void recv_done(struct ib_cq *cq,
}

atomic_dec(&sc->recv_io.posted.count);
- atomic_dec(&sc->recv_io.credits.count);
+ current_recv_credits = atomic_dec_return(&sc->recv_io.credits.count);
+
old_recv_credit_target = sc->recv_io.credits.target;
sc->recv_io.credits.target =
le16_to_cpu(data_transfer->credits_requested);
@@ -783,7 +785,8 @@ static void recv_done(struct ib_cq *cq,
* reassembly queue and wake up the reading thread
*/
if (data_length) {
- if (sc->recv_io.credits.target > old_recv_credit_target)
+ if (current_recv_credits <= (sc->recv_io.credits.target / 4) ||
+ sc->recv_io.credits.target > old_recv_credit_target)
queue_work(sc->workqueue, &sc->recv_io.posted.refill_work);

enqueue_reassembly(sc, response, data_length);